1. Field of the Invention
This invention relates in general to a semiconductor device and in particular to a planar-type device having an extremely high breakdown voltage characteristic.
2. Description of the Prior Art
A planar-type semiconductor junction device is disclosed in U.S. Pat. No. 3,555,373, which includes a so-called guard ring. A device of the type disclosed in this U.S. Pat. No. 3,555,373, having a guard ring, has a higher breakdown voltage characteristic than conventional planar devices. A structure of the type shown in this U.S. Pat. No. 3,555,373, however, is still inferior to so-called mesatype devices having a flat pn junction.